Electric heating/warming fabric articles

ABSTRACT

A fabric article that generates heat upon application of electrical power is formed, for example, by knitting or weaving, to form a fabric prebody. An electrical resistance heating element in the form of a conductive yarn is incorporated into the fabric prebody, e.g., laid in, e.g., in the knit-welt or tuck-welt configuration, the electrical resistance heating elements extending between opposite edge regions of the fabric. Conductive elements are provided for connecting the electrical resistance heating elements to a source of electrical power.

This application claims benefit from U.S. Provisional Patent Application60/501,110, filed Sep. 8, 2003.

TECHNICAL FIELD

This invention relates to fabric articles, which generate heat/warmthupon application of electricity.

BACKGROUND

Fabric heating/warming articles are known, e.g., in the form of electricblankets, heating and warming pads and mats, heated garments, and thelike. Typically, these heating/warming articles consist of a fabric bodydefining one or a series of envelopes or tubular passageways into whichelectrical resistance heating wires or elements have been inserted. Insome instances, the electric resistance heating wires are integrallyincorporated into the fabric body during its formation, e.g., by weavingor knitting. Relatively flexible electric resistance heating wires orelements, e.g., in the form of a core of insulating material, e.g.,yarn, about which is disposed an electrical conductive element, e.g., ahelically wrapped metal wire or an extruded sheath of one or more layersof conductive plastic, have been incorporated directly into the woven orknitted structure of a fabric body.

SUMMARY

According to one aspect of the invention, a method of forming a fabricarticle adapted to generate heat upon application of electrical powercomprises the steps of: joining, in a continuous web, by a reverseplaiting circular knitting process, a stitch yarn and a loop yarn toform a fabric prebody, the stitch yarn forming a technical face of thefabric prebody and the loop yarn forming a technical back of the fabricprebody, the loop yarn forming in loops that overlay the stitch yarn atthe technical face and the technical back of the fabric prebody, atspaced-apart intervals, incorporating into the fabric prebody anelectrical resistance heating element laid in, in knit-weltconfiguration, forming the fabric prebody into a fabric body, with theelectrical resistance heating elements extending between opposite edgeregions of the fabric body, and providing conductive elements forconnecting the electrical resistance heating elements to a source ofelectrical power. In some embodiments, the electrical resistance heatingelement is laid in, in tuck-welt configuration, rather than knit-welt.

Preferred embodiments of the invention can include one or more thefollowing additional steps: finishing at least one of the technical faceand the technical back of the fabric body, in a manner avoiding damageto electrical conductivity of the electrical resistance heatingelements, to form a fleece surface region, or finishing the technicalface of the fabric body, in a manner to avoid damage to electricalconductivity of the electrical resistance heating elements, to form afirst fleece surface region, and finishing the technical back of thefabric body in a manner to avoid damage to electrical conductivity ofthe electrical resistance heating elements to form a second fleecesurface region; applying, directly to the continuous web, the conductiveelements for connecting the electrical resistance heating elements to asource of electrical power; incorporating into the fabric body theelectrical resistance heating element, typically in the form of aconductive yarn comprising a core of insulating material and anelectrical resistance heating filament disposed generally about thecore; in some embodiments, the conductive yarn further comprises asheath material generally surrounding the electrical resistance heatingfilament and the core, e.g., sheath material formed by wrapping theelectrical resistance heating filament and the core with yarn;incorporating into the fabric prebody the electrical resistance heatingelement in the form of a conductive yarn comprising an electricalresistance heating filament; connecting the conductive element to asource of electric power and generating heat, the source of electricpower comprising alternating current or direct current, e.g., in theform of a battery, which can be mounted to the fabric article; limitingformation of loops to a central region of the fabric prebody, thecentral region being spaced from edge regions in the fabric body, andproviding the conductive elements for connecting the electricalresistance heating elements to a source of electrical power in the edgeregions of the fabric body; and/or rendering the yarns of the fabricbody hydrophilic or hydrophobic.

According to another aspect of the invention, a fabric article adaptedto generate heat upon application of electrical power comprises a fabricbody, a plurality of spaced apart electrical resistance heating elementsincorporated into the fabric body in the knit-welt lay in configurationand extending generally between opposite edge regions of the fabricbody, and electrical conductor elements extending generally along theopposite edge regions of the fabric body and adapted to connect theplurality of spaced apart electrical resistance heating elements to asource of electrical power. Alternatively, the electrical resistanceheating elements can be incorporated into the fabric body in thetuck-welt lay in configuration.

Preferred embodiments of this aspect of the invention can include one ormore the following additional features. The electrical conductorelements are adapted for connecting the plurality of spaced-apartelectrical resistance heating elements to a power source of alternatingcurrent or to a power source of direct current, e.g., a battery, whichcan be mounted to the fabric body. A series of at least three of theplurality of electrical resistance heating elements are symmetricallyspaced and/or a series of at least three of the plurality of electricalresistance heating elements are asymmetrically spaced. The fabric bodycomprises a knitted body, e.g., a reverse plaited circular knitted, orother circular knitted (such as double knitted, single jersey knitted,two-end fleece knitted, three-end fleece knitted, terry knitted ordouble loop knitted), warp knitted or weft knitted body, or a wovenbody. The fabric body comprises hydrophilic or hydrophobic material. Thefabric body has a technical face formed by a stitch yarn and a technicalback formed by a loop yarn. The loop yarn forms loops that overlay thestitch yarn at the technical face and the technical back of the fabricprebody. The fabric prebody has loops formed only in a center region.The fabric body has fleece formed upon at least one, and preferablyboth, of the technical back and the technical face. The conductive yarnis tied in, e.g., by tuck or welt. The electrical conductor elements, atleast in part, are applied as an electrically conductive paste or as anelectrically conductive hot melt adhesive. The electrical conductorelements can comprise a conductive wire. The conductive yarn cancomprise a core of insulating material, an electrical resistance heatingfilament disposed generally about the core, and a sheath materialgenerally surrounding the electrical resistance heating filament and thecore. Typically, the core comprises a yarn of synthetic material, e.g.,polyester or nylon; the sheath material comprises yarn, e.g., of asynthetic material, such as polyester or nylon, wrapped about theelectrical resistance heating filament and the core; and the electricalresistance heating filament comprises at least one metal filament,typically at least three metal filaments, wrapped helically about thecore, the metal filament of the electrical resistance heating filamentbeing formed of stainless steel. The electrical resistance heatingelement has electrical resistance in the range of about 0.1 ohm/cm toabout 500 ohm/cm. In some embodiments, the electrical resistance heatingelement has electrical resistance of about 190 ohm/m (1.9 ohm/cm), or250 ohm/m (2.5 ohm/cm). In other embodiments of the conductive yarn, thecore and/or the sheath material can be omitted.

An objective of the invention is to provide electric heating/warmingfabric articles, e.g., electric blankets, heating and warming pads,heated garments, etc., into which a plurality of spaced-apart electricresistance heating members, in the form of conductive yarns, areincorporated by a knitting or weaving process. The fabric body of theheating/warming article, including the incorporated electric resistanceheating members, can subsequently be subjected to a fabric finishingprocess, e.g., one or both surfaces of the fabric body can be napped,brushed, sanded, etc., to form fleece. In a planar structure, such as anelectric heating blanket, the electric resistance heating members areconnected at their ends along opposite edge regions of the planar fabricbody, i.e., of the blanket, and can be powered by alternating current ordirect current, including by one or more batteries mounted to theblanket.

The present invention has a number of advantages. For example, thelength of the electric resistance heating element required to make thefabrics described herein (e.g., tied in in the tuck-welt or knit-weltposition) is substantially less than is required for fabrics whichincorporate an electric resistance heating element as a stitch yarn(e.g., 100% knit in), reducing the cost significantly, e.g., in oneparticular example, the length of the electrical resistance element isreduced by about 30%. Furthermore, as the electric resistance heatingelement is not required to go through the full stitch formation, coarser(i.e., relatively thicker) heating elements can be used, which aregenerally less costly, less flexible and less pliable, and have a higherresistance (ohm/meter), than do the finer wires typically preferred forelectric resistance heating elements incorporated as stitch yarn. Theuse of the knit-welt configuration results in the electric resistanceheating element being held securely in place, minimizing the likelihoodof damage during the napping process.

The details of one or more embodiments of the invention are set forth inthe accompanying drawings and the description below. Other features,objects, and advantages of the invention will be apparent from thedescription and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of an electric heating/warming compositefabric article of the invention in the form of an electric blanket;

FIG. 2 is an end section view of the electric heating/warming compositefabric article of FIG. 1, taken at the line 2—2; and

FIG. 3 is a side section view of the electric heating/warming compositefabric article of FIG. 1, taken at the line 3—3.

FIG. 4 is a perspective view of a segment of a circular knittingmachine, and

FIGS. 5–11 are sequential views of a cylinder latch needle in a reverseplaiting circular knitting process, e.g., for use in forming an electricheating/warming composite fabric article of the invention.

FIG. 12 is a somewhat diagrammatic end section view of a preferredembodiment of a conductive yarn for an electric heating/warming fabricarticle of the invention, while

FIGS. 13–16 and 16A are similar views of alternative embodiments ofconductive yarns for electric heating/warming fabric articles of theinvention.

FIG. 17 is a somewhat diagrammatic section view of a segment of atubular knit fabric during knitting.

FIG. 18 is a somewhat diagrammatic perspective view of the tubular knitfabric of FIG. 17.

FIG. 19 is an end section view, similar to FIG. 2, of an electricheating/warming fabric article of the invention with fleece on bothfaces; FIG. 19A is similar view of an electric heating/warming fabricarticle of the invention, e.g., a sheet or the like, without fleece oneither face; and FIG. 20 is an enlarged, plan view of the technical faceshowing an alternative embodiment of a conductor element.

FIGS. 21, 22 and 23 are somewhat diagrammatic representations of otherembodiments of heating/warming fabric articles of the invention, asadapted to be powered by direct current, e.g., an automobile warming orheating pad (FIG. 21), adapted to be powered from an automobile battery;and a stadium or camping blanket (FIG. 22) and a garment (FIG. 23),adapted to be powered from a battery replaceably mounted to the article.

FIGS. 24A and B are somewhat diagrammatic representations of oneembodiment of the invention, in which the knit-welt configuration isused. In FIG. 24A, only the stitch yarn and one electric resistanceheating element are depicted; the loop yarn is omitted for clarity. FIG.24B includes the loop yarn, which lays over the conductive element.

FIGS. 25A and B are somewhat diagrammatic representations of oneembodiment of the invention, in which the tuck-welt configuration isused. In FIG. 25A, only the stitch yarn and one electric resistanceheating element are depicted; the loop yarn is omitted for clarity. FIG.25B includes the loop yarn.

DETAILED DESCRIPTION

Referring to FIG. 1, an electric heating/warming composite fabricarticle of the invention, e.g., an electric blanket 10, adapted togenerate heat upon application of electrical power, consists of a fabricbody 12 having a technical back 14 and a technical face 16. The fabricbody 12 incorporates a plurality of spaced-apart electric resistanceheating elements 18 extending between opposite edge regions 20, 21 ofthe fabric body.

Referring also to FIGS. 4–11, in a preferred embodiment, the fabric body12 is formed (in a continuous web) by joining a stitch yarn 22 and aloop yarn 25 in a standard reverse plaiting circular knitting (terryknitting) process, e.g., as described in Knitting Technology, by DavidJ. Spencer (Woodhead Publishing Limited, 2nd edition, 1996), the entiredisclosure of which is incorporated herein by reference. Referring againto FIGS. 2 and 3, in the terry knitting process, the stitch yarn 22forms the technical face 16 of the resulting fabric body and the loopyarn 25 forms the opposite technical back 14, where it is formed intoloops (25, FIG. 10) extending over the stitch yarn 22. In the fabricbody 12 formed by reverse plaiting circular knitting, the loop yarn 25extends outwardly from the planes of both surfaces and, on the technicalface 16, the loop yarn 25 covers the stitch yarn 22 (e.g., see FIG. 17).As a result, during napping of the opposite fabric surfaces to form afleece, the loop yarn 25 and stitch yarn 22 protect the conductive yarns26 knitted into the fabric body as a laid in yarn.

The loop yarn 25 forming the technical back 14 of the knit fabric body12 can be made of any synthetic or natural material. The cross sectionand luster of the fibers or the filament can be varied, e.g., asdictated by requirements of the intended end use. The loop yarn can be aspun yarn made by any available spinning technique, or a filament yarnmade by extrusion. The loop yarn denier is typically between 40 denierto 300 denier. A preferred loop yarn is a 200/100 denier T-653 Type flatpolyester filament, e.g., as available commercially from E.I. duPont deNemours and Company, Inc., of Wilmington, Del.

The stitch yarn 22 forming the technical face 16 of the knit fabric body12 can be also made of any type of synthetic or natural material in aspun yarn or a filament yarn. The denier is typically between 50 denierto 150 denier. A preferred yarn is a 70/34 denier filament texturedpolyester, e.g., as available commercially from UNIFI, Inc., ofGreensboro, N.C.

Referring now also to FIG. 12, and also to FIGS. 13–16, at spacedintervals during the knitting process, an electric resistance heatingmember 18 in the form of a conductive yarn 26 is incorporated into thefabric body 12 in place of the stitch yarn 22. Referring to FIG. 12, ina preferred embodiment, the conductive yarn 26 forming the electricalresistance heating elements 18 consists of a core 28 of insulatingmaterial, e.g., a polyester or nylon yarn, about which extends anelectrical conductive element 30, e.g., three filaments 31 of stainlesssteel wire (e.g., 316L stainless steel) wrapped helically about the core28, and an outer covering 32 of insulating material, e.g., polyesteryarns 33 (only a few of which are suggested in the drawings) helicallywrapped about the core 28 and the filaments 31 of the electricalconductive element 30. The conductive yarn 26 can be fabricated usingstandard methods, or can be obtained, e.g., from Bekaert FibreTechnologies, Bekaert Corporation, of Marietta, Ga.

The number of conductive filaments in the conductive yarn, and where thefilaments are located, are dependent, e.g., on the end use requirements.For example, in alternative configurations, in FIG. 13, conductive yarn26′ has four filaments 31′ wrapped about core 28′ with an outer covering32′ of polyester yarns 33′; in FIG. 14, conductive yarn 26″ has threefilaments 31″ wrapped by outer covering 32″ of polyester yarns 33″,without a core. Referring to FIGS. 15 and 16, in other embodiments,conductive yarns 37, 37′, respectively, are formed without an outercovering about the filaments 35, 35′, respectively, wrapped about core34, 34′, respectively, the stitch yarn 22 and loop yarn 25 of the fabricbody 12 instead serving to insulate the conductive yarns in theheating/warming fabric article. Referring to FIG. 16A, a conductive yarn37″ without an outer cover or sheath, formed, e.g., of one or more barefilaments (one filament 35″ is shown) can also be formed without aninsulating core, again, with yarn of the fabric body arranged toinsulate the conductive yarns in the heating/warming fabric body. Theresistance of the conductive yarn can be selected in the range, e.g., offrom about 0.1 ohm/cm to about 500 ohm/cm on the basis of end userequirements of the heating/warming fabric article 10. However,conductive yarns performing outside this range can also be employed,where required. In some embodiments, the resistance of the conductiveyarn is about 1.9 ohm/cm (190 ohm/m). In other embodiments, theresistance of the conductive yarn is about 2.5 ohm/cm (250 ohm/m). Thecore of the conductive yarn and the sheath material of the outercovering over the conductive filaments can be made of synthetic ornatural material. In some embodiments, the core and/or sheath are madeof polyester, e.g., about 600 denier polyester, or of nylon, e.g., about140 denier nylon. The outer covering can also have the form of a sleeve,e.g., a dip-coated or extruded sleeve. Conductive yarns of differentconstructions suitable for use according to this invention can also beobtained from Bekaert Fibre Technologies.

In some embodiments, the conductive yarn comprises four wires, of about35 micron diameter, wrapped around a core of 140 denier nylon, with aresistance of about 190 ohms/meter. In other embodiments, the conductiveyarn comprises four wires, of about 35 micron diameter, wrapped around acore of 140 denier nylon, with a resistance of about 250 ohms/meter. Insome embodiments, the conductive yarn comprises about 90 wires, each ofabout 14 microns in diameter, without a core, with a resistance of about70 ohms/meter.

In the preferred method of the invention, the fabric body 12 is formedby reverse plaiting on a circular knitting machine. This is principallya terry knit, where the loops formed by the loop yarn 25 cover thestitch yarn 22 on the technical face 16 (see FIG. 17).

The conductive yarn is incorporated into the knit fabric prebody formedon the circular knitting machine at a specific spacing or distanceapart, D (FIG. 1), for uniform heating in the resulting heating/warmingfabric article 10. In a fabric prebody of the invention, the spacing istypically a function, e.g., of the requirements of heating, energyconsumption and heat distribution in the article to be formed. Forexample, the spacing of conductive yarns can be in the range of fromabout 0.02 inch to about 2.5 inches. However, other spacing can beemployed, depending on the conditions of intended or expected use,including the resistance of the conductive yarns. The conductive yarnscan be spaced symmetrically from each other, or the conductive yarns canbe spaced asymmetrically, with varying spacing, as desired. Also, in afabric body of the invention, the power consumption for each conductiveyarn is generally considerably lower than in the separate heating wiresof prior art devices. As a result, the conductive yarns in a fabric bodyof the invention can be more closely spaced, with less susceptibility tohot spots.

The preferred position of the conductive yarn is laid in, e.g., inknit-welt or tuck-welt configuration. The knit (knit-welt) or tuck(tuck-welt) stitch holds the laid in conductive yarn. The conductiveyarn can be knit symmetrically, i.e., at a specific distance apart, ineach repeat, i.e., the conductive yarn can be laid in at any feed repeatof the circular knitting machine. Alternatively, the conductive yarnscan be knit asymmetrically, with the yarns more closely or widelyspaced, e.g., as desired or as appropriate to the intended product use.Again, the specific number of feeds, and the spacing of the conductiveyarns, is dependent on the end use requirements. In addition, theconfiguration can be, e.g., knit-welt 1×1, 1×2, 1×3, 1×4, 1×5, 2×2, 2×3,2×4, 2×5, or any other suitable configuration, again, depending on theend use requirements. As compared to tuck-welt lay-in, in the knit-weltlay in configuration the knit holds the laid in conductive yarn andkeeps it from shifting or sticking out, minimizing the likelihood ofdamage to the conductive yarn during napping, even in knit constructionwith inherent stretch properties.

FIGS. 24A and 24B illustrates knit-welt lay in configuration, withstitch yarn 102 (white yarn) and electric resistance heating elementyarn 101 (stippled yarn); the loop yarn 103, which is shown in FIG. 24B,would be present in the preferred method of reverse plaiting circularknitting. The loop yarn is omitted from FIG. 24A for simplicity. FIGS.24A and B illustrate a 2×3 knit-welt configuration.

FIGS. 25A and 25B illustrate the tuck-welt lay-in configuration. In someembodiments, the tuck-welt lay-in configuration can be used instabilized knit construction. Referring to FIGS. 25A, and 25B, electricresistance heating element yarn 201 (stippled yarn) is laid in to thestitch yarn 202 (white yarn) in the tuck-welt position. Loop yarn 203(stippled yarn), which would be present in the preferred method ofreverse plaiting circular knitting, is shown in FIG. 25B, and omittedfrom FIG. 25A for simplicity. FIGS. 25A and B illustrate a 1×2 tuck-weltconfiguration.

Referring to FIGS. 17 and 18, the end regions 20, 21 can be formed as apanel 90 in the tubular knit body 92. The edge regions 20, 21 of thefabric body are preferably formed without loops, and in a manner suchthat the edge regions do not curl upon themselves, e.g., the edge regionpanel is formed by single lacoste or double lacoste knitting. The endsportions 36 (FIG. 1) of the conductive yarns 26 extending into the flatregions 20, 21 without loops are thus more easily accessible in the endregions for completing an electrical heating circuit, as describedbelow.

The tubular knit body 92 is removed from the knitting machine and slit,e.g., along a line of stitches 94 marking the desired slit line, tocreate a planar fabric. Alternatively, for increased accuracy, thetubular knit body 92 can be slit on line, e.g., by a cutting edgemounted to the knitting machine.

As described above, in the fabric article 10 of the invention, spacedapart conductive yarns 18 are electrically interconnected in parallel byconductor elements 40, e.g., in a blanket, extending along the edgeregions. However, during the knitting process of formation, a continuouslength of conductive yarn 26′ (FIG. 18) can be inserted continuouslyduring knitting, with the continuous length of conductive yarn onlythereafter being segmented, e.g., by slitting the tubular knit body 92(FIG. 18), into separate, spaced apart conductive yarns 26 to form thefabric article of the invention.

Preferably, the knitted fabric body 12 incorporating the electricresistance heating elements 18 in the form of the conductive yarns isnext subjected to finishing. During the finishing process, the fabricbody 12 can go through processes of sanding, brushing, napping, etc., togenerate a fleece 38. The fleece 38 can be formed on one face of thefabric body 10 (FIG. 2), e.g., on the technical back 14, in the loopyarn, or a fleece 38, 38′ can be formed on both faces of the fabric body10′ (FIG. 19), including on the technical face 16, in the overlayingloops of the loop yarn and/or in the stitch yarn. In either case, theprocess of generating the fleece on the face or faces of the fabric bodyis preferably performed in a manner to avoid damage to the conductiveyarn which is part of the construction of the fabric body 12.Alternatively, referring to FIG. 19A, e.g., for the purpose of providinga fabric article in the form of a sheet 98 or the like, rather than inthe form of a blanket, neither of surfaces 93, 95 can be subjected tofinishing.

The fabric body can also be treated, e.g., chemically, to render thematerial hydrophobic or hydrophilic.

After finishing, and after the fabric body is heat set for width, theelectric resistance heating elements are connected to a source ofelectrical power by conductors 40 in opposite edge regions 20, 21(where, preferably, there are no loops on the surface), thereby tocomplete the electrical circuit. (The conductors or buses 40 can beformed on the technical back 14, as shown in FIG. 1, or they can insteadbe formed on the technical face 16, as seen in FIGS. 19 and 20.) Anysuitable methods can be used to complete the circuit. For example,referring to FIG. 1, the conductor 40 can, at least in part, be appliedin the form of a conductive paste, e.g., such as available commerciallyfrom Loctite Corporation, of Rocky Hill, Conn., or in the form of aconductive hot melt adhesive, conductive tape (with fabric or plasticbase/carrier, or the like. The conductive paste or adhesive can beapplied as a stripe to a surface of the fabric body 10 in electricalconductive relationship with the electrical resistance heating elements18, and then connected to the power source. (If necessary, theconductive yarns can be exposed, e.g., the polyester or nylon coveringyarn can be removed with solvent or localized heat, e.g., by laser; thecovering yarn can be manually unraveled; or the fabric body 10 can beformed with a needle out in the flat regions 20, 21, thus to facilitateaccessibility to each of the conductive yarns.) Alternatively, referringto FIG. 20, the conductor 40′ can consist of localized dots or regions42 of conductive paste applied in electrical contact with exposedportions of the electric resistance heating elements 18, with aconductive metal wire 44 disposed in electrical conductive contact with,and extending, preferably continuously, between, the localizedconductive paste regions 42. The electric conductor 40′ is thereaftercovered by a cloth trim or edging material 46, attached, e.g., bystitching along the edge of the fabric body 10′.

The completed circuit is next connected to a power source to supplyelectrical power to the electrical resistance heating elements for therequired amount of heat generation. For example, referring to FIG. 1, anelectric heating/warming fabric article 10 of the invention (an electricblanket) is adapted for connection to a source of alternating current bymeans of plug 50 on cord 51 for insertion in household outlet 52.Referring to FIG. 21, a warming or heating pad 60 of the invention,e.g., for an automobile seat, is adapted for connection to a source ofdirect current by means of plug 62 on cord 64 for insertion into thecigarette lighter or other power outlet 66 of an automobile. Referringto FIGS. 22 and 23, a stadium or camping blanket 70 and a garment 80 ofthe invention each includes a source of direct current, i.e. a batterypack 72, 82, respectively, e.g., as available from Polaroid Corporation,of Cambridge, Mass., replaceably mounted to the heating/warming fabricarticle, e.g., in a pocket 74, 84, respectively. Referring to FIG. 22,the pocket can be secured by a hook-and-loop type fastener 76.Preferably, for certification by Underwriters' Laboratory (UL7), thevoltage supplied by the power source to the electrical resistanceheating elements is lower than 25 volts, e.g., a Class II UL7 certifiedtransformer can be used to step down a 110 volt power supply to 25 voltsor under.

Also, for improved efficiency during manufacturing, busses or conductors40 can be applied to the fabric body 12 before it is subjected tofinishing. For example, the conductor 40 applied as a continuous stripof conductive paste or adhesive can be applied directly to thecontinuous web, either continuously, or in a predetermined intermittentpattern, e.g., using a print wheel or the like. The fabric body 12, withthe conductors 40 formed thereupon, can thereafter be subjected tofinishing and other steps of manufacturing.

OTHER EMBODIMENTS

It is to be understood that while the invention has been described inconjunction with the detailed description thereof, the foregoingdescription is intended to illustrate and not limit the scope of theinvention, which is defined by the scope of the appended claims. Otheraspects, advantages, and modifications are within the scope of thefollowing claims. For example, any type of yarn can be employed.

1. A method of forming a fabric article adapted to generate heat uponapplication of electrical power, said method comprising: joining, in acontinuous web, by a reverse plaiting circular knitting process, astitch yarn and a loop yarn to form a fabric prebody, the stitch yarnforming a technical face of the fabric prebody and the loop yarn forminga technical back of the fabric prebody, the loop yarn forming in loopsthat overlay the stitch yarn at the technical face and at the technicalback of the fabric prebody; at spaced-apart intervals, incorporatinginto the fabric prebody an electrical resistance heating element, laidin in the welt position; forming the fabric prebody into a fabric body,with the electrical resistance heating elements extending betweenopposite edge regions of the fabric body; and providing conductiveelements for connecting the electrical resistance heating elements to asource of electrical power.
 2. The method of claim 1, wherein the laidin electrical resistance heating element is in tuck-welt configuration.3. The method of claim 1, wherein the laid in electrical resistanceheating element is in knit-welt configuration.
 4. The method of claim 2or 3, comprising the further step of finishing at least one of saidtechnical face and said technical back of the fabric body, in a manneravoiding damage to electrical conductivity of the electrical resistanceheating elements, to form a fleece surface region.
 5. The method ofclaim 2 or 3, comprising the further steps of finishing the technicalface of the fabric body, in a manner to avoid damage to electricalconductivity of the electrical resistance heating elements, to form afirst fleece surface region, and finishing the technical back of thefabric body in a manner to avoid damage to electrical conductivity ofthe electrical resistance heating elements to form a second fleecesurface region.
 6. The method of claim 2 or 3, comprising the furtherstep of applying, directly to the continuous web, the conductiveelements for connecting the electrical resistance heating elements to asource of electrical power.
 7. The method of claim 2 or 3, comprisingthe further step of incorporating into fabric prebody the electricalresistance heating element in the form of a conductive yarn comprising acore of insulating material and an electrical resistance heatingfilament disposed generally about said core.
 8. The method of claim 6,wherein the conductive yarn further comprises a sheath materialgenerally surrounding said electrical resistance heating filament andsaid core.
 9. The method of claim 7, comprising the further step offorming the sheath material by wrapping said electrical resistanceheating filament and said core with yarn.
 10. The method of claim 2 or3, comprising the further step of incorporating into the fabric prebodythe electrical resistance heating element in the form of a conductiveyarn comprising an electrical resistance heating filament.
 11. Themethod of claim 2 or 3 comprising the further step of connecting theconductive element to a source of electric power and generating heat.12. The method of claim 10 comprising the further step of connecting theconductive element to a source of electric power comprising alternatingcurrent and generating heat.
 13. The method of claim 10 comprising thefurther step of connecting the conductive element to a source ofelectric power comprising direct current and generating heat.
 14. Themethod of claim 12 comprising the further step of connecting theconductive element to a source of electric power comprising directcurrent in the form of a battery and generating heat.
 15. The method ofclaim 13 comprising the further step of connecting the conductiveelement to a source of electric power comprising direct current in theform of a battery mounted to the fabric article and generating heat. 16.The method of claim 2 or 3, further comprising: limiting formation ofloops to a central region of the fabric prebody, the central regionbeing spaced from edge regions in the fabric body; and providing theconductive elements for connecting the electrical resistance heatingelements to a source of electrical power in the edge regions of thefabric body.
 17. The method of claim 2 or 3 comprising the further stepof rendering the yarns of said fabric body hydrophilic.
 18. The methodof claim 1 comprising the further step of rendering the yarns of saidfabric body hydrophobic.
 19. A fabric article adapted to generate heatupon application of electrical power, comprising: a fabric body; aplurality of spaced apart electrical resistance heating elementsincorporated into said fabric body, laid in, in the welt position, andextending generally between opposite edge regions of said fabric body;and electrical conductor elements extending generally along saidopposite edge regions of said fabric body and adapted to connect saidplurality of spaced apart electrical resistance heating elements to asource of electrical power.
 20. The fabric article of claim 19, whereinsaid laid in electrical conductor elements are in tuck-weltconfiguration.
 21. The fabric article of claim 19, wherein said laid inelectrical conductor elements are in knit-welt configuration.
 22. Thefabric article of claim 20 or 21, wherein said electrical conductorelements are adapted for connecting said plurality of spaced-apartelectrical resistance heating elements to a power source of alternatingcurrent.
 23. The fabric article of claim 20 or 21, wherein saidelectrical conductor elements are adapted for connecting said pluralityof spaced-apart electrical resistance heating elements to a power sourceof direct current.
 24. The fabric article of claim 23, wherein saidpower source of direct current comprises a battery.
 25. The fabricarticle of claim 24, wherein said battery is mounted to said fabricbody.
 26. The fabric article of claim 20 or 21, wherein said fabricarticle further comprises a power source connected to said plurality ofspaced apart electrical resistance heating elements by said electricalconductor elements, said power source comprising a battery mounted tosaid fabric body.
 27. The fabric article of claim 20 or 21, wherein aseries of at least three electrical resistance heating elements of saidplurality of electrical resistance heating elements are symmetricallyspaced.
 28. The fabric article of claim 27, wherein a series of at leastthree electrical resistance heating elements of said plurality ofelectrical resistance heating elements are asymmetrically spaced. 29.The fabric article of claim 20 or 21, wherein a series of at least threeelectrical resistance heating elements of said plurality of electricalresistance heating elements are asymmetrically spaced.
 30. The fabricarticle of claim 20 or 21, wherein said fabric body comprises a knittedbody.
 31. The fabric article of claim 30, wherein said fabric bodycomprises a reverse plaited circular knitted body.
 32. The fabricarticle of claim 20 or 21, wherein said fabric body comprises a wovenbody.
 33. The fabric article of claim 20 or 21, wherein said fabric bodycomprises hydrophilic material.
 34. The fabric article of claim 20 or21, wherein said fabric body comprises hydrophobic material.
 35. Thefabric article of claim 20 or 21, wherein said fabric body has atechnical face formed by a stitch yarn and a technical back formed by aloop yarn.
 36. The fabric article of claim 35, wherein said loop yarnforms loops that overlay the stitch yarn at the technical face and thetechnical back of the fabric body.
 37. The fabric article of claim 35,wherein said fabric body has loops formed only in a center region. 38.The fabric article of claim 35, wherein said fabric body has a fleeceformed upon at least one of said technical back and said technical face.39. The fabric article of claim 38, wherein said fabric body has afleece formed upon both of said technical back and said technical face.40. The fabric article of claim 20 or 21, wherein said electricalconductor elements, at least in part, are applied as a conductive paste.41. The fabric article of claim 40, wherein said electrical conductorelements comprise a conductive wire.
 42. The fabric article of claim 20or 21, wherein said electrical conductor elements, at least in part, areapplied as a conductive hot melt adhesive.
 43. The fabric article ofclaim 20 or 21, wherein said electrical resistance heating element hasthe form of a conductive yarn comprising a core of insulating material,an electrical resistance heating filament disposed generally about saidcore, and a sheath material generally surrounding said electricalresistance heating filament and said core.
 44. The fabric article ofclaim 43, wherein said core comprises a yarn of synthetic material. 45.The fabric article of claim 44, wherein said synthetic material ispolyester.
 46. The fabric article of claim 44, wherein said syntheticmaterial is nylon.
 47. The fabric article of claim 43, wherein saidelectrical resistance heating filament comprises at least one metalfilament wrapped helically about said core.
 48. The fabric article ofclaim 47, wherein said electrical resistance heating filament comprisesat least three metal filaments wrapped helically about said core. 49.The fabric article of claim 47, wherein said at least one metal filamentof said electrical resistance heating element is formed of stainlesssteel.
 50. The fabric article of claim 43, wherein said electricalresistance heating element has electrical resistance in the range ofabout 0.1 ohm/cm to about 500 ohm/cm.
 51. The fabric article of claim50, wherein said electrical resistance heating element has electricalresistance of about 1.9 ohm/cm.
 52. The fabric article of claim 43,wherein said sheath material comprises yarn wrapped about saidelectrical resistance heating filament and said core.
 53. The fabricarticle of claim 52, wherein said sheath material comprises a yarn ofsynthetic material.
 54. The fabric article of claim 53, wherein saidsynthetic material is polyester.
 55. The fabric article of claim 53,wherein said synthetic material is nylon.
 56. The fabric article ofclaim 20 or 21, wherein said electrical resistance heating element hasthe form of a conductive yarn comprising an electrical resistanceheating filament and a sheath material generally surrounding saidelectrical resistance heating filament.
 57. The fabric article of claim56, wherein said electrical resistance heating filament comprises atleast one metal filament.
 58. The fabric article of claim 56, whereinsaid electrical resistance heating filament comprises at least threemetal filaments.
 59. The fabric article of claim 57, wherein said atleast one metal filament of said electrical resistance heating elementis formed of stainless steel.
 60. The fabric article of claim 56,wherein said electrical resistance heating element has electricalresistance in the range of about 0.1 ohm/cm to about 500 ohm/cm.
 61. Thefabric article of claim 56, wherein said electrical resistance heatingelement has electrical resistance of about 1.9 ohm/cm.
 62. The fabricarticle of claim 56, wherein said sheath material comprises yarn wrappedabout said electrical resistance heating filament.
 63. The fabricarticle of claim 62, wherein said sheath material comprises a yarn ofsynthetic material.
 64. The fabric article of claim 63, wherein saidsynthetic material is polyester.
 65. The fabric article of claim 63,wherein said synthetic material is nylon.
 66. The fabric article ofclaim 20 or 21, wherein said electrical resistance heating element hasthe form of a conductive yarn comprising a core of insulating materialand an electrical resistance heating filament disposed generally aboutsaid core.
 67. The fabric article of claim 66, wherein said corecomprises a yarn of synthetic material.
 68. The fabric article of claim67, wherein said synthetic material is polyester.
 69. The fabric articleof claim 67, wherein said synthetic material is nylon.
 70. The fabricarticle of claim 66, wherein said electrical resistance heating elementcomprises at least one metal filament.
 71. The fabric article of claim70, wherein said electrical resistance heating filament comprises atleast three metal filaments.
 72. The fabric article of claim 70, whereinsaid at least one metal filament of said electrical resistance heatingelement is formed of stainless steel.
 73. The fabric article of claim66, wherein said electrical resistance heating element has electricalresistance in the range of about 0.1 ohm/cm to about 500 ohm/cm.
 74. Thefabric article of claim 67, wherein said electrical resistance heatingelement has electrical resistance of about 1.9 ohm/cm.
 75. The fabricarticle of claim 67, wherein said electrical resistance heating elementhas electrical resistance of about 2.5 ohm/cm.
 76. The fabric article ofclaim 20 or 21, wherein said electrical resistance heating element hasthe form of a conductive yarn comprising an electrical resistanceheating filament.
 77. The fabric article of claim 76, wherein saidelectrical resistance heating filament comprises at least one metalfilament.
 78. The fabric article of claim 76, wherein said electricalresistance heating filament comprises at least three metal filaments.79. The fabric article of claim 77, wherein said at least one metalfilament of said electrical resistance heating element is formed ofstainless steel.
 80. The fabric article of claim 76, wherein saidelectrical resistance heating element has electrical resistance in therange of about 0.1 ohm/cm to about 500 ohm/cm.
 81. The fabric article ofclaim 76, wherein said electrical resistance heating element haselectrical resistance of about 1.9 ohm/cm.
 82. The fabric article ofclaim 76, wherein said electrical resistance heating element haselectrical resistance of about 2.5 ohm/cm.